COLD gas plasma as a novel approach to improve wear performance of UHMWPE

Ultra height molecular weight polyethylene (UHMWPE) is widely used in joint replacements devices. It is highly biocompatibility but its reduced resistance to wear is a serious limitation to employment as, potentially, the longevity of such devices is reduced. Numerous techniques have been employed to increase the resistance to wear of UHMWPE with different degree of success; but they all require expensive equipments and high level of safety precaution as based on radiation and or high temperatures. Moreover, a stabilization step is often required to prevent material degradation adding to process complexity and cost. Treatment using cold atmospheric-pressure gas plasma is a relative low-cost process that has been already utilized to decontaminate surfaces; furthermore it has also been applied as surface modification method. In this work, for the first time, atmospheric cold gas plasma is proven capable of enhancing the wear performance of UHMWPE without reducing the cytocompatibility of the material. The exposure to a cold atmospheric-pressure gas plasma made in a Helium and Oxygen mixture causes a higher level of crosslinking of the polyethylene chains; as a results of this higher cross-linking, the materials hardness is greater on the surface of treated materials than untreated.